runnermedic

hi
i need to know if there is someone who did this efan for the condenser.
i was looking for one efan and i dont know wich one to choose a 9 inch or a 10 inch pull/pusher,is just for the condenser the cooling system is working ok i just want to remove some heat from that unit knowing that there is no condenser fan maybe a small fan can do the job moving some fresh air in stop traffic.

KZN185W

iTrader: (1)

I've seen some using either a Denso or Bosch fan. the small support tabs will need to be fabricated depending on the the fan size and fan config. What they did was use the ac compressor wiring to activate the fan. when the compressor engages, the fan turns on. a better way would be to use the temperature setting in the cabin ac controls as switch for the fan. this way you save fuel a bit compared to the first option

runnermedic

I was thinking that maybe a 9-10 inch will work but i don want to have any airflow interference so im pointing for a 7 inch one.
About the wiring the a/c Comp b (+) is the easy way to go ,i only need a relay and a diode to prevent electricity to run back to the a/c b(+)
Im going to take apart the front grill and take some measurements.
I will post some pics later, now i have to order the efan first

KZN185W

iTrader: (1)

I don't know about the temperature in Puerto Rico, but a 7-inch fan looks small to me. a 10-inch fan would be better and more effective.

about the electricity going back, kindly expound on it if you don't mind.

runnermedic

Temps here are around 80-90f in the day.so youre right.
About the current issue,i going to add a diode in the b(+) a/c wire because the efan wen not in use it can produce current (generator effect) so this way no current will enter the a/c curcuit

KZN185W

iTrader: (1)

another lesson learned! Thanks!

what diode size/spec would you recommend?

runnermedic

Check my mercury villager efan swap thread there is a wiring diagram for a 2 speed fan

runnermedic

You can use a 1n4001 diode 50v 1amp drop.
Another thing is that non reversible fans have diodes already in it.a push/pull fan have none

or 1N5820,3A 20V

runnermedic

10 inch fan wont fit,took measurements and the space to fit it is almost 8 inches so im going to order the 7 inch,anyway is better than nothing!!!

KZN185W

iTrader: (1)

I talked to a friend of mine who has the fan and told him about having a diode as the fan installed in his truck is a push/pull and currently in the push configuration. His reply is this:

"i dont really know if the fan can generate current at free-wheel speeds. however, assuming that it can, the current will go direct to the relay, which at that point is off, meaning the solenoid is disconnected. Now the positive wire that goes from the fan to the relay is directly connected to that open solenoid (the other side of the solenoid being the direct B+ power source), so then the current cannot flow past and has nowhere to go. The current cannot go to the a/c power line because that line is only used to trigger the solenoid switch, BUT IT DOES NOT PROVIDE THE POWER THAT FLOWS THRU THE SOLENOID".

"its important to differentiate between the power that triggers the solenoid switch and the power that flows thru the solenoid once the switch has been triggered. if there is a direct connection between the trigger power line(a/c power) and the power line of the fan then there will be no need to trigger the relay. and then even if the a/c system is off, when you drive, as you pick up speed the a/c compressor will come to life just from the power generated by the free-wheeling fan".

suncomb1

I purchased a 6" fan on ebay for my engine oil cooler and it works great. If you wire up an isolating relay to the fan motor you will never get any electrical feerdback to the A/C system.

runnermedic

your friend is totally right, there's no need to but there's always a maybe or just in case ,what if the relay or anything else goes bad?
you don't want current flowing back to the circuit right,well this is why i use diodes in efans is not a thing that you have to,but i feel more secure knowing that the diodes are there if something goes bad.
im not an electrical engineer,but think of this.
if you're in the HW and the efan is moving from the airflow it will produce current so what happen when you run current to something that is producing it?
in that case im going to add another 2 diodes,so they will be 3, one for the ign+ one for the + load and one for the a/c signal+.

if someone with an electrical engineer degree can help with this feel welcome to do so,meanwhile im going to stick with it!!!!!

don't take me bad but this is an electrical poor man insurance!!!!!!
i really appreciate your interest in this thread and as you said everyday we learn something new.

runnermedic

A motor is an inductor, just like a coil (including an ignition coil), and so resists instaneous changes in current, also a turning dc motor is also a dc generator, so there will be voltage across the motor until it stops turning (the "backflow" mentioned, not a big deal, though). The main concern is removing power from the motor results in the motor trying to hold the same current flow through it, except that the relay contacts are open and there is no path for current to go. The current has to go SOMEWHERE, and the easiest place is often to arc across the contacts. It is the same reason a set of ignition points will burn out, unless itself protected by a condensor (capacitor).

KZN185W

iTrader: (1)

I like your idea of having a back-up in case the relay fails. and no, i don't and won't feel bad about it. it's always good to have an exchange of ideas.

with the relay in between, where do you plan to have the diode installed, a/c compressor side or fan side?

Thanks again.

runnermedic

Well i did some efan swaps for a few friends with 3vz,and always installed one in the a/c+ and one in each load +,i do remember of one that works for about a month and then locks up i had to take it all apart and found that the brushes were stuck and burned that one only used the a/c diode the others i made were using loads+ and ac+ dioded , so im going to use 3, a/c+,load+ and ignition.
I ordered this efan


7" 1500 CFM 2250 RPM 12v Electric Cooling Slim Radiator Fan
http://www.ebay.com/itm/BMW-Black-Pu...-/330751985395



1N5400 50V/3A SILICON RECTIFIER

URL: http://pages.ebay.com/link/?nav=item...d=360431233814

KZN185W

iTrader: (1)

i see. Thanks again.

Fan looks good and it's a new model so it should last long being a BMW

runnermedic

Lol....
That guy sells them with different brands but is the same one

runnermedic

efan arrived today,ill be working on it tomorrow,will post some pics of the job

KZN185W

iTrader: (1)

looking forward to the pics..

runnermedic

and here are the pics